This invention relates to a fuel control system for controlling the fuel flow of a compression ignition engine and more particularly to a speed sensitive device for decreasing fuel flow to the engine under certain engine loading conditions.
Compression ignition engines commonly utilize a governor to position a fuel pump control member to maintain the engine speed within a predetermined operating range. When the load on the engine decreases, engine speed increases and the governor automatically retracts the fuel pump control member to reduce the supply of fuel to the engine. When the load on the engine is increased, the engine speed tends to decrease and the fuel pump control member is advanced to supply more fuel to the combustion chambers of the engine. A fixed full load stop is normally provided to limit the travel of the fuel pump control member and thus the maximum volume of fuel directed to the engine for establishing the full load speed of the engine. When the engine is lugged down below a certain speed due to increased loading applied to the engine, more fuel is directed to the combustion chambers than can be burned resulting in inefficient and incomplete burning of the fuel. This causes an increase in the noxious exhaust emission and smoke from the engine.
Other approaches to solving the above problem are taught by the constructions disclosed in U.S. patent application Ser. No. 409,864 filed Oct. 26, 1973 now U.S. Pat. No. 3,916,862 by Clouse et al. and in U.S. patent application Ser. No. 519,578 filed Oct. 31, 1974 now U.S. Pat. No. 3,911,885 by Hammond, both of which are assigned to the assignee of the present application.